Saturn - The Second Gas Giant and the Sixth Planet.

Quick Nav

Saturn Saturn

This is the second biggest planet in our Solar system. In Roman mythology, Saturn is the god of agriculture. The associated Greek god, Cronus, was the son of Uranus and Gaia and the father of Zeus (Jupiter). Saturn is the root of the English word "Saturday."

Saturn has been known since prehistoric times. Galileo was the first to observe it with a telescope in 1610. He noted its odd appearance but was confused by it. Early observations of Saturn were complicated by the fact that the Earth passes through the plane of Saturn's rings every few years as Saturn moves in its orbit. A low resolution image of Saturn therefore changes drastically. It was not until 1659 that Christiaan Huygens correctly inferred the geometry of the rings. Saturn's rings remained unique in the known solar system until 1977 when very faint rings were discovered around Uranus (and shortly thereafter around Jupiter and Neptune).

In 1655 Huygens discovered the moon Titan and Cassini discovered four more later that century that he named the Sidera Lodoicea. Here's some of Saturn's important attributes:

Distance from Sun:
Mean: 9.53 AU
Perihelion: 1,352.55 x 106 km
Ahelion: 1,514.50 x 106 km
Size:
Volume: 82,713 x 1010 km3
Diameter: 120,536 km
Mass: 5.68 x 1026 kg
Motion:
Year: 29.4 E Years
Day: 10.7 E Hours
Other:
Density: 687 kg per m3
Surface Temperature: -130°C or 97°K

Saturn is visibly flattened (oblate) when viewed through a small telescope; its equatorial and polar diameters vary by almost 10% (120,536 km vs. 108,728 km). This is the result of its rapid rotation and fluid state. The other gas planets are also oblate, but not so much so. Saturn is the least dense of the planets; its specific gravity (0.7) is less than that of water.

Saturn Rings and Shepherds

Like Jupiter, Saturn is about 75% hydrogen and 25% helium with traces of water, methane, ammonia and "rock", similar to the composition of the primordial Solar Nebula from which the solar system was formed. Saturn's interior is similar to Jupiter's consisting of a rocky core, a liquid metallic hydrogen layer and a molecular hydrogen layer. Traces of various ices are also present.

Saturn's interior is hot (12000 K at the core) and Saturn radiates more energy into space than it receives from the Sun. Most of the extra energy is generated by the Kelvin-Helmholtz mechanism as in Jupiter. But this may not be sufficient to explain Saturn's luminosity; some additional mechanism may be at work, perhaps the "raining out" of helium deep in Saturn's interior.

Saturn's ring and moon placement.

Two prominent rings (A and B) and one faint ring (C) can be seen from the Earth. The gap between the A and B rings is known as the Cassini division. The much fainter gap in the outer part of the A ring is known as the Encke Division (but this is somewhat of a misnomer since it was very likely never seen by Encke). The Voyager pictures show four additional faint rings. Saturn's rings, unlike the rings of the other planets, are very bright (albedo 0.2 - 0.6). Click Here to see the rings.

 

Sidera Lodoicea

Sidera Lodoicea - Tethys, Dione, Rhea and Iapetus Tethys Dione Rhea Iapetus

Similar to Gallileo and his Galilean moons Giovanni Domenico Cassini (1625-1812) discovered four moons around Saturn:

  1. Iapetus - October 25th, 1671
  2. Rhea - December 23rd, 1672
  3. Tethys - March 21st, 1684
  4. Dione - March 21st, 1684

Giovanni Domenico CassiniCassini named this group of moons in honor of king King Louis XIV of France. Sidera Lodoicea means Loisian Stars. King Louis XIV was king from 1643 to 1715 and was the patron of the Paris Observatory. Cassini was the director of the Observatory from 1671 to 1712.

Cassini published his discoveries in his Découverte de deux nouvelles planètes autour de Saturne in 1673 and in the Journal des sçavans in 1686.

These moons are four of the five largest around Saturn (after Titan).

See All of Saturn's Moons


Missions to Saturn

Saturn is closer to us and is easier to get to. We've sent a few probes out it's way, but the most important is the Cassini-Huygens currently in orbit around the planet.

# Name Launch Date Closest Approach Mission End Date
1 Pioneer 11 04/05/1973 09/01/1979 09/30/1995
2 Voyager 1 09/05/1977 11/12/1980 Active
3 Voyager 2 08/20/1977 08/26/1981 Active
4 Cassini/Huygens 10/15/1997 Orbit Active

Saturn Symbol Gallery

These are pictures of Saturn and it's moons.

Cassini - SaturnCassini - Saturn Cassini - Dione Behind EnceladusCassini - Dione Behind Enceladus Cassini - Dione Behind PandoraCassini - Dione Behind Pandora Cassini - Dione Behind RheaCassini - Dione Behind Rhea Cassini - Dione and EnceladusCassini - Dione & Enceladus Cassini - Epimetheus, Rings and TitanCassini - Epimetheus, Rings & Titan Cassini - Epimetheus and JanusCassini - Epimetheus & Janus Cassini - Epimetheus' ShadowCassini - Epimetheus' Shadow Cassini - Iapetus Behind TethysCassini - Iapetus Behind Tethys Cassini - Mimas and PrometheusCassini - Mimas & Prometheus Cassini - Pandora, Rhea Behind TethysCassini - Pandora, Rhea Behind Tethys Cassini - Pan and RingsCassini - Pan & Rings Cassini - Prometheus, Pandora and the F-RingCassini - Prometheus, Pandora & the F-Ring Cassini - Rhea Behind MimasCassini - Rhea Behind Mimas Cassini - Rings, Pandora and RheaCassini - Rings, Pandora & Rhea Cassini - Rings and Rhea Behind EnceladusCassini - Rings & Rhea Behind Enceladus Cassini - Rings, Rhea, Dione and AtlasCassini - Rings, Rhea, Dione & Atlas Cassini - Saturn 1Cassini - Saturn 1 Cassini - Saturn 2Cassini - Saturn 2 Cassini - Saturn 3Cassini - Saturn 3 Cassini - Saturn 4Cassini - Saturn 4 Cassini - Saturn 5Cassini - Saturn 5 Cassini - Saturn 6Cassini - Saturn 6 Cassini - Saturn Clouds 1Cassini - Saturn Clouds 1 Cassini - Saturn Clouds 2Cassini - Saturn Clouds 2 Cassini - Saturn Clouds 3Cassini - Saturn Clouds 3 Cassini - Saturn Clouds 4Cassini - Saturn Clouds 4 Cassini - Saturn Clouds 5Cassini - Saturn Clouds 5 Cassini - Saturn Clouds 6Cassini - Saturn Clouds 6 Cassini - Saturn North CloudsCassini - Saturn North Clouds Cassini - Saturn RheaCassini - Saturn Rhea Cassini - Saturn, Rhea, Enceladus and TethysCassini - Saturn, Rhea, Enceladus & Tethys Cassini - Saturn South Clouds 1Cassini - Saturn South Clouds 1 Cassini - Saturn South Clouds 2Cassini - Saturn South Clouds 2 Cassini - Saturn South Clouds 3Cassini - Saturn South Clouds 3 Cassini - Saturn South Clouds 4Cassini - Saturn South Clouds 4 Cassini - Saturn South Clouds 5Cassini - Saturn South Clouds 5 Cassini - Thethys, Enceladus and the E-Ring Cassini - Thethys, Enceladus & the E-Ring Hubble - Saturn 1Hubble - Saturn 1 Hubble - Saturn 2Hubble - Saturn 2 Hubble - Saturn SeasonsHubble - Saturn Seasons Voyager 1 - Saturn 1Voyager 1 - Saturn 1 Voyager 1 - Saturn 2Voyager 1 - Saturn 2 Voyager 1 - Saturn 3Voyager 1 - Saturn 3 Voyager 1 - Saturn 1Voyager 1 - Saturn Clouds 1 Voyager 2 - Saturn 1Voyager 2 - Saturn Clouds 1 Voyager 2 - Saturn 2Voyager 2 - Saturn Clouds 2 Voyager 2 - Saturn 3Voyager 2 - Saturn Clouds 3  

Back to Home